B80-6-29 A Rare Case of Rapid Onset Toxicity From Pembrolizumab (Keytruda) in Non-small Cell Lung Cancer

Abstract Pembrolizumab (Keytruda) is a PD 1 inhibitor that boosts anti-tumor response but is also known to cause immune-related adverse events (irAEs) including pneumonitis. This is a rare case where it acutely developed within twenty-six hours of initiating therapy for recurrent squamous non-small cell lung cancer. Our patient was a 72-year-old woman with chronic obstructive pulmonary disease, ulcerative pancolitis (UC), and recurrent non-small cell lung cancer for which her oncologist started carboplatin, paclitaxel, and pembrolizumab. The patient elected to start therapy despite the risk for autoimmune side effects due to her history of UC. Twenty-six hours after her infusion, she developed acute hypotension, bradycardia, and hypoxia. Her initial providers assumed she was suffering from pneumonia and started antibiotics. She received a CT of her chest significant for left lung ground-glass opacity and bilateral pleural effusions. This was unrelated to cardiac dysfunction as her echo showed a normal ejection fraction. A left-sided pleural catheter was placed with transudative pleural fluid studies. In context of her risk factors (UC, COPD, combination therapy), recent Pembrolizumab infusion, CT findings, negative infectious work up, and failure to respond to antibiotics or pleural fluid drainage, it was determined that the respiratory failure was likely from pembrolizumab induced pneumonitis rather than bacterial pneumonia or cardiac effusions. Pembrolizumab induced pneumonitis occurrence is about 3-5% and is radiographically defined by ground glass opacities, organizing pneumonia, or diffuse alveolar damage, but this generally takes place after months of therapy. This case is a rare, very early onset lung toxicity from pembrolizumab with only two other noted cases on review of literature, one case at forty-eight hours with respiratory failure and another twenty-four hours with pneumonitis and cardiac arrest. Prior risk factors that can increase one’s risk for pneumonitis from pembrolizumab include radiation, chronic obstructive pulmonary disease, and combination treatment. Therapy involves steroids and IVIG; however, this requires rapid diagnosis and timely treatment. In conclusion, the patient had risk factors for this rare presentation and was even warned about autoimmune effects by oncology. However, when she arrived in the intensive care unit, the appropriate therapy was not even considered before she expired. In situations like this, a better outcome may be achieved with early recognition by assessing risk factors, response to current therapy, and consulting oncology. Further studies are warranted to understand how many early onset cases of pneumonitis from pembrolizumab are being missed as respiratory failure for other reasons. This abstract is funded by: None